In U.S. Pat. No. 5,059,166 by Fischell et al there is described a radioisotope stent for the treatment of arterial stenoses. In recent clinical trials, this radioisotope stent has been shown to decrease neointimal hyperplasia within the stent but in some patients an "edge effect" has been observed. The edge effect is characterized by a short length of stenosis that appears just proximal or just distal to the edge of the stent. When the edge effect is severe, the blood flow in that artery can be severely diminished.